Conventionally, imaging devices, such as a charge coupled device (CCD), and a complementary metal-oxide semiconductor (CMOS), etc. that convert received light into an electrical signal by performing photoelectric conversion have been known.
In general, in such an imaging device, to adjust color reproducibility to a level that matches a luminosity of the human eye, an infrared cut filter (i.e., so-called IR cut filter) is provided to be located in front of the imaging device, thereby removing infrared light from light entering the imaging device.
However, as in security cameras, there are cases in which sensitivity is considered more important than color reproducibility, and in such a case, light including infrared light has to be received by an imaging device.
Thus, to satisfy both of the above-described conditions, an imaging device according to PATENT DOCUMENT 1 is configured so that an IR cut filter is installed in front of the imaging device according to the amount of light. Specifically, an IR cut filter is attached to an aperture, and when the amount of light entering the imaging device is small, the IP cut filter is moved to an evacuation position in conjunction with releasing of the aperture. On the other hand, when the amount of light entering the imaging device is large, the IR cut filter is moved back to be installed in front of the imaging device in conjunction with stopping of the aperture down to a predetermined aperture value.